Question

please answer maths legends please

Answer 1

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▶ Question - Find :

(i) the lateral or curved surface area of a closed cylindrical petrol storage tank that is 4.2 m in diameter and 4.5 m high.

(ii) how much steel was actually used, if 1/12 of the steel actually used was wasted in making the tank.



▶ Explanation :-



Height ( h ) of cylindrical tank = 4.5 m


Radius ( r ) of the circular end of cylindrical tank = ( 4.2 / 2 ) = 2.1 m


i) Lateral or curved surface area of tank = 2πrh


= 2 × 22 / 7 × 2.1 × 4.5


= 44 × 0.3 × 4.5


= 59.5 m^2


Therefore, CSA of tank = 59.5 m^2


ii) Total surface area of tank = 2πr ( r + h )


= 2 × 22 / 7 × 2.1 ( 2.1 + 4.5 )


= 44 × 0.3 × 6.6


= 87.12 m^2


Let A m^2 steel sheet be actually used in making the tank


=> A ( 1 - 1 / 12 ) = 87.12


=> A ( 11 / 12 ) = 87.12


=> A = 87.12 × 12 / 11


=> A = 95.04 m^2


Therefore, 95.04 m^2 steel was used in actual while making such a tank




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